// 一像素边框
border-1px-bottom($color)
  position: relative
  &::after
    position: absolute
    left: 0
    bottom: 0
    width: 100%
    content: ''
    border-bottom: 1px solid $color

border-1px-top($color)
  position: relative
  &::before
    position: absolute
    left: 0
    top: 0
    width: 100%
    content: ''
    border-bottom: 1px solid $color
